To Us Investigators, The Concept

Everyone Is Free To Set Up An Opinion And To Adduce Proofs In Support Of It. Whether, Though, A Scientist Shall Find It Worth His While To Enter Into Serious Investigations Of Opinions So Advanced Is A Question Which His Reason And Instinct Alone Can Decide. If These Things, In The End, Should Turn Out To Be True, I Shall Not Be Ashamed Of Being The Last To Believe Them.

Similarly, Many A Young Man, Hearing For The First Time Of The Refraction Of Stellar Light, Has Thought That Doubt Was Cast On The Whole Of Astronomy, Whereas Nothing Is Required But An Easily Effected And Unimportant Correction To Put Everything Right Again.

What Mach Calls A Thought Experiment Is Of Course Not An Experiment At All. At Bottom It Is A Grammatical Investigation.

The Ego Is As Little Absolutely Permanent As Are Bodies.

Ordinarily Pleasure And Pain Are Regarded As Different From Sensations.